Remote graphic communication, particularly in the form of remote chalkboards, is gaining popularity. Such systems, sometimes called telautograph systems, allow persons at an input chalkboard to write on the board in the conventional manner. An image of the written material will then appear on the remote viewing screen. Such systems are particularly helpful in lectures where classrooms may be distributed around the country or around the world. One such system is shown in the G. M. C. Fisher, U.S. Pat. No. 3,706,850, dated Dec. 19, 1972. An example of the surface which is used to accept the input is shown in U.S. Pat. No. 3,959,585, dated May 25, 1976, issued to H. C. Mattes. These two patents are hereby incorporated by reference as though they had been reproduced herein in their entirety.
While telautograph systems serve their intended purpose, a practical problem remains to be overcome. In operation, as a lecture progresses the remote chalkboard becomes filled with information, such as equations or graphs. Usually, at some point, the lecturer wishes to highlight some previously written symbol. From the local or transmitting end, this simply requires the lecturer to place the chalk or stylus next to the location on the chalkboard where the listeners' attention should be focused. Viewers at the local end then known precisely where the lecturer is pointing. However, at the remote end, the viewers do not have the benefit of seeing the lecturer and thus must rely strictly on their ability to locate a dot, i.e., the point at which the lecturer is touching the surface of the sending screen. Under the best of conditions, this would be difficult. However, because of transmission and screen resolution problems where random background dots are not uncommon, it is virtually impossible for a remote end viewer to know where a lecturer is pointing. Thus, the viewer must struggle to follow the lecturer.
The lecturer, on the other hand, knowing that the remote viewer cannot see the chalk's position, will typically circle the point on the board where attention should be directed. However, once circles, squares and other extraneous materials begin to appear on the screen the information content can become degraded to the point where the whole purpose of the remote transmission can become lost.
This same problem, or a variation thereof, is evident when the lecturer tries to erase or correct a small portion of the board. The viewer must scan the entire remote screen trying to see what letter, number, exponent, or punctuation has changed. Under these conditions, what begins as an aid to communication quickly becomes a hindrance.
As a possible solution to these problems those familiar with graphic terminals will focus their attention on known cursor systems where the cursor marks the position of the input. Typically, however, such cursor systems are arranged to either (1) locate for a person at a terminal (user) the position of the next mark to appear on the screen, or (2) allow the user to move the cursor over the face of the screen thereby locating a point on the screen at which some future action (usually by the machine) is to be taken. In these situations, the cursor is either used as an aid to the user or as an aid to the machine. In the first situation, the machine generates a cursor at the next anticipated screen position and in the second instance the user generates the position manually. In neither of these situations is the cursor arranged to assist either a remote viewer or a lecturer in solving the problems discussed for telautograph systems.